9 ms·
Kosmos 482: questions around a failed 1972 Venera lander still orbiting Earth
- Donckele 4y agoDid anyone get when the ETA is for impact and predicted location?
- colordrops 4y agoI doubt that it's predictable that far out. Perhaps a particular band of land, but not some specific area.
- _moof 4y agoDepending on how it's modeled, 2024 to 2027 (with earlier being higher likelihood), or 2023 to 2025. No way to predict location but it'll be somewhere between 52°N and 52°S.
- ars 4y agoCan anyone explain how it's possible for the apogee to reduce so much, while the perigee barely changes? Wouldn't the air resistance that lowers the apogee also affect the perigee? Or is it specifically because the object is being slowed at perigee, that the apogee lowers, while the perigee doesn't change much because the apogee is in vacuum?
- ncmncm 4y agoThat is about it.
- deleted 4y ago[deleted]
- pvg 4y agoThink of a very very elliptical orbit, one that's nearly a line and consider what happens when you take a bit of energy off the orbiting object. At perigee, when the energy is almost entirely kinetic, you're mostly just changing the velocity, rather than altitude of the object. At apogee, when the energy is almost entirely potential, it's the other way round - the change is almost entirely one of altitude. This is further stretched by the much more 'visible' effect of potential energy changes on altitude than of kinetic energy changes on velocity.
- avereveard 4y agothe atmospheric drag at perigee happens perpendicular to the object speed, which is tangential to the gravity field, so the object doesn't get shifts on it's vertical speed, only it's energy, having less to convert in potential energy (i.e. apogee height) in the thereabout of perigee you have two arms, one inbound and one outbound. the horizontal component of the drag for both is all in the direction against the travel and slow the craft without changing the vertical component of its speed the vertical component of the drag (for as long as the craft has the energy to get's outside of the dense atmosphere) kind of cancels out, as the drag force inbound pushes against your down velocity vector and the drag force outbound pushes against your up velocity vector. there is however a small energy loss due to the fact that the journey trough the atmosphere isn't perfectly simmetrical, since you're losing speed along all the way, the inbound leg is shorter than the outbound leg, causing the vertical component of the drag going outside to slightly exceed the component of the vertical drag coming in - so your perigee does change little by litte due this (and other more nuanced effects, but we're painting with a large brush here) - this asymmetry gets stronger the more you stay in the atmosphere and the furthest you dip in the dense area, until you ultimately don't have the energy to escape anymore. the fact that the atmosphere isn't on/off like that but has a long boundary layer stretching far from the dense parts kinda complicates things a little more, because drag is applied the whole circle, but not by that much.
- wcoenen 4y agoThe rule of thumb you can use to make this intuitive: A change in velocity at a certain point x on an orbit will change the entire orbit, except that orbit will still continue to go through that one point x. So slowing down at perigee will not alter the perigee. (It is actually the most delta-v efficient way to lower the apogee.)
- taylorfinley 4y agoNapkin math: earth's surface area is ~510 million square kilometers. The lander is described as fitting in a 1-meter protective shell. So we have a roughly 1 in 510 billion chance of standing in the lucky spot. (This of course would only be accurate if all square meters of the earth's surface were equally likely to be hit. Not the case since the lander appears to be orbiting the equator.)
- pvg 4y agoThe distribution of people is not uniform over the potential impact area, which is, as you mention yourself, not the whole surface of the earth. The error bars on this are too huge even by napkin standards, for this to work as an estimate.
- deleted 4y ago[deleted]
- deleted 4y ago[deleted]
- femto 4y agoThat's an English billion (10^12), given that there are a million square metres to the square km? Mind you, I wouldn't want to be standing within 18m of where it lands, so either definition of "billion" does make sense.
- tgv 4y agoI think 100 can be unsafe. It'll go fast, it's heavy, and hard. Things will fly around.
- _moof 4y agoOrbital inclination is 52°. That leaves about 400 million km^2.
- adastra22 4y agoYou’re off by a few orders of magnitude.
- MrBuddyCasino 4y agotl;dr on why its relevant: „The reentry of the Kosmos 482 Descent Craft will not be your standard reentry. The Descent Craft was designed to survive entry through the dense atmosphere of Venus. It will therefore likely survive reentry into the Earth’s atmosphere intact and make a crash landing (it is extremely unlikely that the parachute system will still work after more than 50 years in space). This will therefore be a high-interest reentry.“
- deleted 4y ago[deleted]
- deleted 4y ago[deleted]
- adesanmi 4y agoWould we be able to shoot it down before it hits anything?
- perihelions 4y agoThere's a diplomatically-sensitive moratorium on shooting down space objects. Technically, sure. https://www.reuters.com/world/us/us-will-not-conduct-direct-ascent-anti-satellite-missile-tests-harris-says-2022-04-19/ https://www.reuters.com/world/us/us-will-not-conduct-direct-...
- zeckalpha 4y agoChina or Russia could?
- SkittyDog 4y agoIf you shoot at something that is falling... it's still gonna fall, even if you hit it, brrak it up, etc. Whatever matter is there before will still be there after the hit, but on a less predictable trajectory. If you break it up into pieces before it re-enters the atmosphere, you may get a higher proportion of burnup, because small chunks means lower overall ballestic coefficient per mass... But hitting stuff in orbit is difficult, and we would have a very hard time predicting the results.
- russellbeattie 4y agoIf a chunk of Soviet space junk falls on someone's house, does the Russian Federation just shrug and say, "That was the USSR, bruh, sorry." They must have assumed responsibility for the Soviet space program, right? It's sort of like firing a bullet into the air... Doesn't matter how long it takes to come down, it's still your fault if it kills someone.
- deleted 4y ago[deleted]
- WalterBright 4y agoIt seems unlikely that terminal velocity of a bullet would be terribly dangerous.
- Someone 4y agohttps://www.newscientist.com/lastword/mg25233622-900-can-bullets-fired-upwards-cause-injuries-when-they-return-to-earth/ https://www.newscientist.com/lastword/mg25233622-900-can-bul...: “If you see a soldier shooting into the air, run for shelter first and cringe later. Falling bullets cause injuries and deaths.” I expect a great difference depending on the size of the bullet.
- eesmith 4y agohttps://en.wikipedia.org/wiki/Celebratory_gunfire https://en.wikipedia.org/wiki/Celebratory_gunfire lists a few deaths. Given the number of people who celebrate with gunfire, it's indeed not terribly dangerous overall. Nevertheless, "it's still your fault if it kills someone."
- WalterBright 4y ago"They found that while bullets traveling on a perfectly vertical trajectory tumble on the way down, creating turbulence that reduces terminal velocity below that which would kill, it was very difficult to fire a bullet in this near-ideal vertical trajectory. In practice, bullets were likely to remain spin-stabilized on a ballistic trajectory and fall at a potentially lethal terminal velocity." So I'm not completely wrong. Of course, if you fire a bullet non-vertically, it's much more likely to have a lethal velocity when it returns.
- JacobAldridge 4y agoAn interesting note right at the end, so in case anyone missed it: this same launch is believed to be the source of 5 titanium "spaceballs" that fell onto New Zealand in 1972. While the odds are low of any space debris hitting land, it was the photo in this article that surprised me - I was thinking billiard ball size debris, not this - http://www.stuff.co.nz/the-press/4542804/Government-report-on-space-balls-released http://www.stuff.co.nz/the-press/4542804/Government-report-o...
- adzm 4y agoThat article mentions them dangling a wrist watch over the space ball to see if it was radioactive. How would this work?
- nynx 4y agoPerhaps tritium in the watch hands.
- pvg 4y agoTritium is itself radioactive and used in watches to make a luminescent material glow. I think zinc sulphide was common and it would probably glow if lit up enough. Not sure you want to be near something that makes your watch dial markings glow visibly more than the radium or tritium that's in the paint, though.
- Hextinium 4y agoThe tritium interacts with a phosphor through beta decay, so presumably if you hung a watch near it the phosphor would glow brighter with higher concentration of beta decay. Basically a sort of visual Geiger counter.
- pvg 4y agoZinc sulphide, from brief googling, seems like it would glow in anything so if this was a thing, it probably makes most sense for gamma radiation since the 'detector' isn't being massively lit up by that internally already.
- travisgriggs 4y agoA water splashdown is the highest probability. But I think even with the 52 degree envelope, Russia is still probably the largest landmass in that envelope? So I take ironic pleasure knowing it’s more likely to smack back into Russia than any other country. (I’m making an educated assumption about the geography, but could be wrong)
- femto 4y ago52 degrees pretty well lines up with Russia's southern border. Virtually no overlap.
- Gravityloss 4y agoYes, makes sense, because of physics. When the Soviet Union wanted to launch something to space, it did it as close to the equator as possible. That way you get the most boost from the spinning earth. (If you're not using a polar orbit.) So they used a southern point of Soviet union in Tyuratam in Kazakhstan, better known as Baikonur.
- pengaru 4y agoIs this the origin of the name for the film SPACEBALLS?
- jl6 4y agoPretty sure it’s just because the word balls is funny.
- qbasic_forever 4y agoThe movie came out 15 years later and I doubt anyone remembered or knew about titanium balls falling on New Zealand. Spaceballs was always meant to be a direct parody of Star Wars. I remember from that time people were more freaked out about Skylab falling down to earth--there were novelty t-shirts with a big target and "Skylab target" printed on them, all the late night TV hosts joked about it, etc. Skylab falling back to earth was a big event: https://www.youtube.com/watch?v=zoVXuKQ__0s https://www.youtube.com/watch?v=zoVXuKQ__0s
- an1sotropy 4y agoWell there went 40 minutes of my time. thanks :)
- SentientAtom 4y agoHow fascinating it would be to recover it for posterity.
- bencollier49 4y agoI'm trying to get my head around what sort of damage an object of this size travelling at terminal velocity would do.
- skykooler 4y agoThe lander mass is around 1000 lb, so picture the results of dropping a grand piano off a skyscraper.
- Terry_Roll 4y ago> The balls, which had Russian markings, were used to pressurise fuel tanks or as stabilisation jets, the report states. Spent a bit of time in the metal trade, sometimes various metals that can best be described as oddities from Sheffield would be heading south, one such time some metal pieces were on this lorry no bigger than a chunk of cheese or hash brown thats broken off, clearly its been part of a larger plate of metal, but its magnetic strength was so strong it needed a screw driver to leverage it off anything it was stuck to. Never seen anything as strong magnetically since, but it had became a sort of competition with people/visitors asked to try to pull it off what other metal it was stuck to. > 20 kilogram, titanium sphere, > It is not something you would sell to a scrap dealer,'' he said. The titanium being sold as scrap would come down in bars which had been angle-grinded all over to produce long metal splinters so that it could only be handled with a fork lift, the splinters would go through gloves if you tried to handle it. That shows to what lengths some scrap metals were "processed" in order to avoid being stolen.